A Simplified Determination of Creep Properties of Steels by Measuring their Crack Opening Displacements (COD) at Elevated Temperatures

Abstract:

The testing of creep resistance (for example σ_{1%/100000 h}) of metals has been required for a long time (about 10 years) and some methods have been worked out to decrease testing time. The application of these methods has some difficulties. Now we have worked out a new empirical method to reduce testing time, namely COD measuring at an elevated temperature. The paper presents this method, which makes it possible to determine creep properties by measuring the materials COD at an elevated temperature. To determine COD we use notched samples with different radii and we tear them at an elevated temperature. The determination of COD is based on the Czoboly Radon method. By opening three different radii notches we approximate to zero radius which gives the COD. Master Curves of COD and creep resistance connections were drawn at 500 °C, which is not dependent on materials and they can be used for determining Creep Properties from COD measured at 500 °C. This method can be used for the comparison of the creep resistance of materials and for that of the creep properties of different zones of welded joints. The method is found useful in technical practice.

• Periodical: Materials Science Forum (Volume 729)
• Pages: 114-119
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.729.114
• Online since: November 2012
• Authors: Béla Palotás
• Keywords: COD Measuring on Elevated Temperature, Connection between Creep Properties and COD, Crack Opening Displacement (COD), Creep Resistance, Creep Rupture Test, Czoboly Radon Method

References

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[2] Boris Ule, Monika Jenko, Roman Sturm Accelerated small-punch creep testing, Materiali v Tehnologije 36 (2002) 6.

[3] J. C. Radon and E. Czoboly, Material toughness versus specific fracture work, Proc. Int. Conference, Mechanical Behaviour of Materials, Kyoto, Japan, I, pp.543-557, (1972).

[4] B. Palotas, Y. Elarbi. Determination of the Creep properties of Creep Resistant Martensitic Steels at Elevated Temperatures from their crack Opening Displacements (COD)", The IIW Conference "Welding & Materials Technical - Economical - Ecological Aspects, 05-06 July 2007, Dubrovnik, Croatia, 2007, p.: 235 -242.

DOI: 10.4028/www.scientific.net/msf.729.114